Discovery on Thursday became the first spaceship from the retired US shuttle fleet to enter its permanent home as a museum artifact, marking a solemn end to the 30-year manned spaceflight program.

The oldest surviving US shuttle, Discovery flew 39 missions to space beginning in 1984 and its transition from space-flying giant to tourist attraction drew mixed emotions from NASA veterans and space fans alike.

Discovery ended its last mission to space in March 2011, and the return to Earth of Atlantis in July 2011 marked the end of the US shuttle program, leaving Russia as the only nation capable of sending astronauts to space.

"The space shuttle program gave this country many firsts and many proud moments," said NASA administrator Charles Bolden at a branch of the Smithsonian National Air and Space Museum outside the US capital.

"We are now happy to share this legacy with millions of visitors."

Several thousand tourists eager to see the shuttle up close streamed into the Steven F. Udvar-Hazy Center in suburban Virginia, where volunteers handed out miniature American flags and a Marine Corps band played.

"I feel like a little kid today," said aerospace engineer Kelly Scroggs, 24, passing a pair of young boys dressed as astronauts in the crowd.

Later, 15 of the shuttle's 31 living commanders along with a handful of other astronauts who flew to space aboard Discovery walked along the left side of the celebrated spacecraft as it was towed to the tarmac outside to rest nose to nose with the shuttle Enterprise, which has been at the museum for years.

Among them were Eileen Collins, the first woman to pilot and command a space shuttle aboard Discovery and Steve Lindsey, who commanded its final space flight last year.

"It is a happy day but it is also a very sad day," said Fred Gregory, who commanded the Discovery 1989 and was among the astronauts clad in blue escorting the charred, aging shuttle to the museum.

"Discovery pretty much represents the rest of the fleet that we have all been a part of for a really long time," Gregory told AFP.

"And since there is nothing immediate on the horizon it is sad because perhaps a legacy has ended, the leadership that America has had in the past might not be as strong now."

Famous space traveler John Glenn, who was the first American to orbit the Earth in 1962 and later returned to space aboard Discovery in 1998, said he regretted the end of the shuttle program but hoped Discovery would inspire future generations.

"The unfortunate decision made eight and a half years ago to terminate the shuttle fleet, in my view, prematurely grounded Discovery and delayed our research," Glenn said.

"But those decisions have been made," he added. "And now we move on with new programs and possibilities unlimited."

Discovery is the first of the three remaining shuttles that flew in space to enter a museum. Endeavour and Atlantis will follow in the coming months.

Two other shuttles, Challenger and Columbia, were destroyed in accidents. Challenger disintegrated shortly after liftoff in 1986 and Columbia broke apart on re-entry to Earth in 2003. Both disasters killed everyone on board.

Discovery drew cheering crowds and some tears from onlookers earlier this week when it toured the skies over Washington one last time, piggybacking atop a Boeing 747 that NASA keeps specifically for transporting the shuttles.

Several private companies are competing to be the first to build a space capsule that would replace the US shuttles operated by NASA for three decades.

While a test cargo mission by SpaceX to the International Space Station is planned for April 30, the prospect of US-driven human space flight remains several years away.

"I went into engineering because of the space shuttle program," said Loretta McHugh, 35, standing near a group of tables where private companies handed out flyers about their aims for returning Americans to space.

"I know the commercial efforts are taking off, literally, but I also think there needs to be a federal program too. Hopefully this is just a short break for us."

Later this year, Endeavour will move from the Kennedy Space Center in Florida to the California Science Center in Los Angeles.

The shuttle Atlantis, also still in Florida, will make just a short hop to a new exhibit at the Kennedy Center's visitor complex.

Enterprise, a prototype shuttle that never flew in space, will head to New York City on April 23 for a flashy flyover of the Big Apple aboard the same Boeing 747 that Discovery rode, before going on display at the Intrepid Sea, Air and Space Museum.